title: Expression of all six human Torque teno virus (TTV) proteins in bacteria and in insect cells, and analysis of their IgG responses.
abstract: Torque teno virus (TTV) is a non-enveloped human virus with a circular ( approximately 3800 nt) ssDNA genome. TTV transcription results in three viral mRNAs and six proteins, the function or antigenicity of which are unknown. The six open reading frames of TTV genotype 6 were expressed in bacteria and insect cells. Expression of the ORF1/1-encoded protein was inefficient, while expression of the others was successful, with ORF1 and ORF1/2 as arginine-rich region depleted. All six recombinant TTV proteins were antigenic. Of healthy adults, 11/25 (44%) showed strong IgG reactivity with one or more proteins. Four subjects, two of whom were genotype-6-DNA positive, were followed. One of the latter showed concurrently a strong IgG response against the ORF1 protein. The other showed appearance of IgG against the ORF2 protein concomitantly with resolution of the genotype-6 viremia. The genotype-6 sequences remained unaltered for years, suggesting that some mechanisms other than amino acid substitutions play a role in TTV immune evasion.
authors.affiliation: Department of Virology, Haartman Institute and Helsinki University Central Hospital Laboratory, Haartmaninkatu 3, P.O. Box 21, University of Helsinki, FIN-00014, Finland. laura.kakkola@helsinki.fi
authors.forename: Laura
authors.initials: L
authors.lastname: Kakkola
authors.forename: Heidi
authors.initials: H
authors.lastname: Bondén
authors.forename: Lea
authors.initials: L
authors.lastname: Hedman
authors.forename: Niina
authors.initials: N
authors.lastname: Kivi
authors.forename: Susanna
authors.initials: S
authors.lastname: Moisala
authors.forename: Jaakko
authors.initials: J
authors.lastname: Julin
authors.forename: Jussi
authors.initials: J
authors.lastname: Ylä-Liedenpohja
authors.forename: Simo
authors.initials: S
authors.lastname: Miettinen
authors.forename: Kalle
authors.initials: K
authors.lastname: Kantola
authors.forename: Klaus
authors.initials: K
authors.lastname: Hedman
authors.forename: Maria
authors.initials: M
authors.lastname: Söderlund-Venermo
mesh_terms: D000328:Adult; D000818:Animals; D000914:Antibodies, Viral / Q000096:biosynthesis; D000956:Antigens, Viral / Q000096:biosynthesis / Q000235:genetics; D001483:Base Sequence; D002460:Cell Line; D004266:DNA Virus Infections / Q000276:immunology / Q000821:virology; D004279:DNA, Viral / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression; D005814:Genes, Viral; D006801:Humans; D007074:Immunoglobulin G / Q000096:biosynthesis; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology; D018411:Spodoptera; D022783:Torque teno virus / Q000235:genetics* / Q000276:immunology*; D014764:Viral Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000276:immunology*
chemical_list: D000914:Antibodies, Viral; D000956:Antigens, Viral; D004279:DNA, Viral; D007074:Immunoglobulin G; C446939:ORF1 protein, TT virus; C524331:ORF2 protein, Torque teno virus; D011994:Recombinant Proteins; D014764:Viral Proteins